Questions for the future of humanity: who will prosper and who will be left behind in a world of 10 billion people?

Lena and Sahid have never met, and probably won't in the future either. Lena lives in the Leipzig of 2050, a peaceful and sleepy historical city of middle-aged professionals. Lena is in the middle of her career as a pharmacist. She is 51 years old and more than twenty years separate her from retirement age. She and her husband no longer have to support their only daughter, who recently graduated from university, but it worries them that in the future they will have to take care of their aging parents, who are now in their 80s and 90s and meanwhile are in quite good health. Sahid is 22 years old and has four brothers and sisters. He is not married, has no job, and lives in a crumbling slum on the outskirts of Lagos, Nigeria. Sahid, his brothers and sisters face a very different kind of struggle: the struggle to find a job in a job market that is stressed and flooded with young workers and the struggle to find a place to live and obtain clean water.

Lena is troubled by chronic diseases. Sahid is more at risk from malaria. Germany is struggling to adapt its pension, health and service systems to a shrinking population that is living longer than ever before. Nigeria is struggling to build roads and build schools and sanitation facilities in its growing population.

It is hard to imagine a life more different than the lives of Lena and Sahid. But these two different fictional characters embody many challenges that await us in the future. The distribution of the human population is about to change in unprecedented ways over the coming decades. And it will force governments and the international community to rethink what to do to protect the health and well-being of people all over the world. The decisions they make today will determine whether the future of people like Lena and Sahid will be better or worse.

population boom

About half a century ago, attention was focused on only one global trend in the world's population: its total size. the entomologist Paul R. Ehrlich of Stanford University warned in his 1968 bestseller "The population bomb", that rapid population growth will mean that food and other resources will not be enough for the world's population and will lead to the starvation of millions. But the reality that Ehrlich feared did not materialize. The green revolution Rapidly improved food security, and a combination of economic development and access to education and family planning have reduced the birth rate in most of the world. By 19700 the population growth rate had already declined after reaching a peak of 2% in the 60s.

Even so, population growth is like a moving train: even when it slows down, it has a lot of momentum left that makes it difficult for it to come to a stop. Today, the global birth rate continues to decline, but billions more are still expected to join the world's population over the next few decades. The UN estimates that by 2050 the world's population will number about 9.7 billion people. The chance that the train will stop completely, meaning that the world's population will stabilize or start to decrease before 2100, is 23%.

But when we focus only on such predictions, predictions of the most general kind, we lose sight of important details. Half of the population growth between now and 2050 is expected to occur in nine countries, five of them in Africa. Meanwhile, the birth rate in the industrialized world is falling and life expectancy is increasing. According to UN estimates, the number of people aged 60 and over in the world is expected to double or more over the next 34 years. The number of people aged 80 and over will triple. Many of these elders will live in Europe. It is estimated that by 2050 more than a third of the total population in Europe will be over 60 years old. Jack A. Goldstone, professor of political science at George Mason University and director of the Public Policy Institute at the Hong Kong University of Science and Technology, calls this challenge to the world order we know as "The new population bomb".

Germany and Nigeria represent the two opposite poles of the changing global dynamics. One is a rich but rapidly aging country, whose cities are shrinking and whose government faces ever-increasing pension costs. The other is a nation of young people, which will have to find room in its cities for more immigrants from the villages and more babies: trends that join other problems such as climate change and infectious diseases. Regarding Nigeria more than other places, Uma Hans Groth, chairman of theForums World for Demography and Aging in St. Gallen, Switzerland, history cannot teach us what the future holds: "As humans, we are not ready to face or accept such great changes."

growing pains

By 2050, the population of Nigeria is expected to surpass that of the United States and make Nigeria the third largest country in the world in terms of population size: according to UN estimates, it is expected to more than double and reach 398.5 million people. If so, during the years of Sahid's life as a young man, he will witness a further reduction of the resources that his country can distribute among its inhabitants, resources that are already scarce today. "Think about it," he says John Bongaerts, Vice President of the New York City Population Council. "Everything man-made will have to be doubled: every school, every clinic, every bridge."

In 2015, the United Nations Population Division updated its estimates regarding Africa's population growth. In some respects the change reflected good news. Thanks to advances in public health and improvement in indicators such as the infant mortality rate and death from AIDS, life expectancy in sub-Saharan Africa is increasing.

But the other half of the story is that the birth rate has not fallen as quickly as many had hoped. Across the continent, the total birth rate, meaning the number of children a woman gives birth to during her lifetime, continues to stand at 4.7 children per woman. In Nigeria the birth rate is 5.7 children per woman. Theoretically, Nigeria could benefit from a "demographic transition phase": a period during which the birth rate declines, and a large adult labor force is available, without large numbers of parents or children dependent on them for support. Countries that reduce both the birth rate and the death rate and successfully complete the demographic transition phase by improving education, employment, and other factors that contribute to economic development, can enjoy a "demographic dividend" that catapults them forward to a higher level of development. But in Nigeria, as in other parts of sub-Saharan Africa, the birth rate fell only slightly, then stopped falling and stopped at a high level.

Demographers attribute this persistent lack of change to a variety of possible factors: from the continued influence of tribal culture to the lengthening window of time during which women give birth. according to Ocynrinula Bankula, a demographer at the Guttmacher Institute in New York City, "People still think in terms of security in old age", they want many children to take care of them in their old age. "They think less about the need to invest in children and more about the desire to ensure this security for themselves."

A high birth rate that refuses to decrease will add to the alarming amount of threats Nigeria is already struggling with: poverty, hunger, infectious diseases, and the negative effects of climate change. About 240 million people in sub-Saharan Africa, one in four, do not receive adequate nutrition. 30 million children are currently underweight, according to Population Information Bureau (a non-profit organization that collects and distributes information in order to help deal with demographic and environmental problems). When Sahib, his brothers and sisters grow old, the region will have to feed hundreds of millions more mouths. The "Alliance for a Green Revolution in Africa" ​​organization (agra) is one of the organizations working to improve food security on the continent. The organization was founded in 2006 by Kofi Annan, the former UN Secretary General, and for six years he also headed it. The organization works to promote changes in agricultural policy and helps small farmers obtain improved quality seeds, organic fertilizers, and basic equipment. Sub-Saharan Africa needs all the help it can get. "The concentration of population growth in the poorest countries may make it difficult for certain countries to eliminate poverty, fight hunger and malnutrition, expand the services of the health and education systems, and improve the provision of basic services and infrastructure," says Francois Peltier From the Population Department of the United Nations.

Moreover, within countries like Nigeria, the distribution of population growth will not be uniform. Today, the highest birth rate is in the north of the country, an area where most of the resources are scarce. As a result, an increasing number of people from the north of the country will join the martyr and his family members in the city of Lagos. This rate is part of a wider global trend. By 2050, urbanization and general population growth are expected to add more than 2.5 billion people to the world's urban population, and 90% of this urban population growth is expected to occur in Asia and Africa.

Urbanization is often a positive phenomenon, accompanied by an increase in education, a decrease in the birth rate and stable economic growth. Well-planned cities reduce the land areas used by humans, use them more efficiently and contribute to a more efficient use of energy. Henrik Ordel, a political science expert at the Peace Research Institute in Oslo, Norway, found with his colleagues that urbanization can even reduce the chance of conflict outbreaks.

But the fact that countries like Nigeria are undergoing urbanization at a much lower level of economic development than before means that by 2050 a large part of the world's population will be concentrated in cities that are not prepared to provide adequate health and sanitation services and other services. This situation could expose Saheed to infectious diseases, which tend to thrive in densely populated areas with many immigrants. Urbanization is considered one of the main factors that contributed to the early spread of the AIDS disease in Africa. By 2050, the slums of Lagos could become breeding grounds for tuberculosis and malaria.

As Nigeria continues to move up the economic ladder, and more people buy cars and consume more electricity, air pollution could become another health threat. The growth of giant cities in Asia in recent decades allows us to see what might happen in Africa. Recent data from a study on the global burden of disease, injuries and risk factors shows that in 2010, in China alone, air pollution caused 1.2 million deaths and 25 million years of lost life.

The high birth rate is the source of many of Nigeria's problems, but ironically, if Nigeria succeeds in reducing the birth rate, this change may also have a less desirable side effect: as the birth rate falls, the relative number of young people in their teens and 20s in the population will increase . If the economy cannot provide enough jobs, Bongaarts said, "we will have young people unemployed, or with too few jobs. They will be unhappy, convenient for exploitation, and will contribute to crime and the lack of security." Some researchers believe that such "youth waves" contributed to the outbreak of the uprisings of the "Arab Spring" in North Africa and the Middle East.

To be successful in the coming years, countries like Nigeria must act simultaneously to improve education, youth employment and make family planning accessible to young people. It will be a major operation, but not impossible. 40 years ago, few predicted the rapid decline in birth rates that occurred in Bangladesh, Indonesia and Iran. If Sahid finds a job and gets married, he may decide to settle for fewer children than his parents had, so that he can finance their studies. The more young people behave like him, the more likely Nigeria will be to turn the potential danger into an advantage, and reap demographic gains. Such changes in the population made a decisive contribution to the economic recovery of other countries, including Brazil, China and South Korea.

an aging population

In Germany, a completely different change is taking place. Lena was born in 1999, when the German economy was the engine of Europe's economic growth and enjoyed an abundance of workers. In 2050, Germany's population is expected to decrease to below 74.5 million, compared to 80.7 million today. Almost 40% of Germans will be 60 and older, while people aged 15 to 59, who make up the majority of the workforce, will be only 48% of the population: a 19% decrease compared to their proportion in the population today. Certain regions in Germany make it possible to see this future already today. The head of the town of Otenstein in the northwest of the country, a man in his 70s, announced last year that he would give free land to couples with small children. The goal: to prevent the closing of the local school.

A situation similar to that of Germany also arose in Asia, Europe and Latin America. The UN estimates that 11 countries, including Japan and Ukraine, may lose 2015% or more of their population by 15. The media are already often dealing with the shrinking population in Germany and its neighbors. A problem that may occupy the policy makers towards 2050 will be a continuous economic slowdown as a result of the lack of workers and young taxpayers.

One can be tempted to think of immigration as a way to fill the manpower shortage. The United Nations predicts that between 2015 and 2050 Germany will be one of the largest receivers of immigration in the world. The hundreds of thousands of desperate Syrian families, crossing the Mediterranean Sea with all their belongings on their backs, have already turned the spotlight on this issue. As the population continues to grow in sub-Saharan African countries, and especially if young people like Saheed are unable to find work in their countries, the flow of immigrants may increase and tie the future of Germany and Nigeria together. Experts sometimes claim that this trend will help balance the aging population. But according to Goldstone, "tens of millions of immigrants will be necessary to balance the small number of young people in Germany, the Netherlands and other countries with low population growth" - and, on the other hand, to ease population pressures in countries with rapid population growth such as sub-Saharan African countries.

This means that even if Leipzig receives a modest amount of immigrants, its population will continue to shrink. The city may have difficulty adjusting the water, electricity and other services to the low level of use that will result from this process, and may face the problem by raising prices, a change that people of working age like Lena will have to bear. The shrinking city can therefore be an expensive city.

Germany may also find itself facing new health challenges, as improvements in health and life expectancy will change the major diseases it will have to deal with. Lena's parents, for example, belong to the group known as "the oldest old": those aged 80 and over, who are estimated to make up 14.4% of Germany's population in 2050. Their chances of dying from cancer or heart attacks will be smaller than those of previous generations, but their chances of suffering from dementia will increase. Insanity is a disease whose prevalence increases as life expectancy increases, and it will therefore become more and more common, unless a cure is found. "In the past, people just died before they got Alzheimer's disease. Now that doesn't happen," says Axel Bersch-Suppen, director of the Institute for the Economics of Aging in Munich and principal investigator of the Survey of Health, Aging and Retirement in Europe, a long-term study of more than 45,000 Europeans aged 50 and over.

Economically, aging in Western Europe is not a uniform phenomenon. It is not only the result of low birth rates, but also of a sharp increase in life expectancy and significant improvements in people's health and well-being. Europeans not only live longer but also stay healthy and able to work for much longer. Over the past twenty years, life expectancy has increased in Europe, and today it reaches slightly more than 80 years. Health indicators are improving all over Europe, according to Barash-Sofan: "Longevity is increasing at a linear rate. There is no sign of the curve flattening." (In the US, on the other hand, the preoccupation with slowing down the rate of aging tends to divert attention from the disappointing trend in life expectancy, which has actually worsened among certain groups, says Barash-Sofan).

There are those who say that in Europe we need to redefine what "old age" is. Sergey Shrebov, a demographer at the International Institute for Applied Systems Analysis in Lexenburg, Austria, suggests treating a person as "aging" only in the last 15 years of his life, which are defined according to the expected life expectancy for a person in his country according to the year of his birth. He says that such an index would better reflect people's abilities and health than the UN's definition, according to which old people are 60 years old and older: "In the 50s, the oldest person to climb Mount Everest was 20 years old A few years ago, an 39-year-old Japanese guy climbed the mountain."

The pension systems are indeed undergoing profound changes in many European countries. In Germany, the retirement age is currently 65 years and five months, and it is planned to gradually increase to 67 by 2029. But in order for the country to be able to meet the needs of people like Lena's parents, who live more than 80 years, it will be necessary to eventually tie the age Life expectancy retirement, something that has already been done in Norway and Sweden, a change that is not expected to be welcomed with joy. "The problem in Europe is that people like to retire early," says Barash-Sophan, "and this is not a sustainable situation."

Demographic gravity

The fates of Sahid and Lena depend to a large extent on what will happen now. Demographers claim that proper planning for the future, both in Nigeria and in Germany, will make it possible to deal with future population changes. Demography, says Goldstone, is similar to gravity: you have to accept the fact of its existence and act accordingly. "If you know how to deal with gravity, you can make planes rise in the air," he says. But you have to plan the plane well so that it can fly. "A stable government and a growing economy can exist both when the population grows and when it shrinks. But we need to invest wisely, manage the economy well, train the workforce to be more productive, and adapt the programs to the welfare needs of the different age groups that change over time."

In a way, Nigeria and Germany are at opposite ends of a global continuum. Between these two extremes are dozens of other countries, which will also play changing roles with the changes in population distribution. In the US, both aging and growth of the population as a whole are expected. By properly addressing, already in the present, issues such as health services, urban infrastructure, education, food security, and ensuring pensions, countries from all parts of the global continuum can ensure a better life for future generations.

Efforts to maintain global stability will have to include countries with large populations whose economies are growing, including Brazil, China, India and Mexico. This means that changes will have to take place in the structure of international bodies such as the G7 and NATO in a way that better reflects the changing face of the world and ensures that the money flows towards public health and dealing with the resource and infrastructure challenges, not only of the industrialized nations but of the entire world. By creative thinking and determined action that begins well in advance, humanity may be able to prevent the new population bomb from exploding.

For more articles in the series:

• Questions for the future of humanity: How will climate change change us?
• Questions for the future of humanity: What geological imprint will we leave behind?
• Questions for the future of humanity: Will we survive the economic disparities?
• Questions for the future of humanity: Will we defeat aging?